1. Field of the Invention
This invention relates to a speed-shift apparatus for a manual sheet winch for marine use, especially for a manual marine sheet winch with a multi-staged speed change mechanism.
2. Description of the Prior Art
Different type sheet winches with speed-change mechanisms, for instance, three-staged speed-change mechanisms, have been used heretofore.
One of the conventional constructions of the sheet winch comprises two sets of gear trains with high reduction ratios, one set of gear train with a reduction ratio close to direct driving, and a speed-shift means, e.g., a clutch, for selecting the desired one of the gear trains.
This type winch construction has a drawback in that, when operation of the speed-shift means is necessary, a shift lever separate from a driving handle must be actuated, so that it is impossible to actuate both the handle and the lever by only one hand. Sheet winches for yacht and the like vessels are generally required to be operable by only one hand, because one hand is continuously occupied by a rope for handling the vessel, and the other hand is only available for operating the sheet winch. Accordingly, the sheet winch of the aforesaid conventional construction has a shortcoming in that the hand for operating the driving handle of the winch has to be moved to the speed-shift lever for shifting the speed-change ratio.
Another construction of the sheet winch in the prior art uses a speed-shift disk coacting with a ratchet wheel engageable with pawls, instead of using the speed-shift lever actuating a clutch or the like. However, this speedshift disk also requires the simultaneous use of two hands for the sheet winch, e.g., for simultaneous operations of the driving handle and the speed-shift disk. Thus, complete operation of the sheet winch by only one hand is not possible yet.
In another construction of the sheet winch in the prior art, a connecting means for connecting the driving handle to the drum of the sheet winch is mounted on the driving handle itself, so that the connection between the driving handle and the drum can be regulated by the connecting means on the driving handle. With this construction using the connecting means, however, the construction of the driving handle becoms special and such driving handle cannot be used in common for winches of other types.